Stabilization of polyvinyl fluoride



United States Patent 3,454,517 STABILIZATION 0F POLYVINYL FLUORIDEClifford A. Neros, Willoughby, and Charles P. Tomba,

Painesville, Ohio, assignors to Diamond Shamrock Corporation, acorporation of Delaware No Drawing. Filed Feb. 11, 1966, Ser. No.526,720 Int. Cl. C08f 45/62, 45/58 US. Cl. 260-30.4 Claims ABSTRACT OFTHE DISCLOSURE A thermally stable resinous vinyl fluoride compositionincorporates an aliphatic polyol and zinc dicyclohexyl dithiophosphinateinto a vinyl fluoride polymer containing at least 75%, by Weight, of thetotal weight of the polymer of vinyl fluoride. Additional stabilizingadditives to the foregoing mixture include the thiodialkanoic aciddiesters. The composition can be applied from the dispersion systemthrough the use of a latent solvent and may be colored through the useof pigments. Substrates may be coated with the thermally stable resinousvinyl fluoride composition of this invention.

The present invention relates to the stabilization of fluorinecontaining Vinyl resins, particularly vinyl fluoride resins.Specifically, the present invention is particularly applicable to thestabilization of pigmented vinyl fluoride polymer resin compositions andcoated articles therefrom.

Vinyl fluoride polymers particularly in the form 'of films and coatings,display a combination of excellent properties, e.g., weatherability(resistance to degradation when exposed to outdoor conditions),pliability and strength (flexural, tensile and tear) well withindesirable ranges. Due to the fact that vinyl fluoride polymerdeteriorates upon heating prior to its reaching the high temperaturesnecessary to prepare a film or coating and the polymer is insoluble incommonly used volatile solvents, such as acetone, petroleum ether,iso-octane, xylene, etc., it has been found necessary to disperse thevinyl fluoride resin in the form of discrete particles in a suitableliquid medium which has substantially no solvent action on the polymerat room temperature, but which is capable at elevated temperatures ofcoalescing the polymer particles. However, vinyl fluoride polymers stillare subject to severe degradation and consequent discoloration uponexposure to the high temperatures necessary for fusion of the polymer.Lack of such stability is a serious obstacle to the commercialexploitation of this polymer.

While considerable activity has been undertaken in the field of polymerstabilization in an attempt to improve heat stability of vinyl-typeresins and numerous additives have been suggested and tried as polymeradditives for incorporation in vinyl resins to prevent or minimize such3,454,517 Patented July 8, 1969 deterioration, none of these stabilizershas been found effective for a vinyl fluoride polymer system,particularly a pigmented vinyl fluoride polymer system. In other Words,the prior art stabilizers or stabilizer systems which are elfective toinhibit the deterioration of a vinyl polymer not containing otheradditives have been found to be ineffective in a vinyl fluoride polymersystem containing latent solvent and pigment. Using a wide variety ofstabilizers and stabilizer systems suggested in the prior art, vinylfluoride polymer coating systems containing latent solvent and pigmentbecome discolored at the fusion temperatures generally employed to bakesatisfactorily the coating to a substrate. To date, there has been foundno stabilizer or stabilizer system effective to prevent discoloration ofboth a vinyl fluoride polymer and a vinyl fluoride polymer systemcontaining the resin, latent solvent therefor and pigment.

Accordingly, it is an object of this invention to provide a stabilizedvinyl fluoride polymer having an increased resistance to colordegradation or deterioration.

It is a further object of the present invention to provide a pigmentedvinyl fluoride polymer system having increased resistance to colordegradation or deterioration upon baking at elevated temperatures.

The above and related objects are achieved by incorporting in the vinylfluoride polymer or vinyl fluoride polymer system comprising vinylfluoride polymer, latent solvent therefor and pigment, a stabilizingquantity of a mixture of an aliphatic polyol having at least two toabout eight alcoholic hydroxyl groups for each two to about fifteencarbon atoms and a dithiophosphinate compound having the followingstructure:

wherein R is :a hydrocarbon radical (aliphatic, straight or branched,cyclic or aromatic, saturated or unsaturated, substituted orunsubstituted) containing about 2 to 18, preferably 3 to 12 carbonatoms.

Examplary of suitable polyols include trimethylolethane,trimethylolpropane, pentaerythritol, dipentaerythritol,tripentaerythritol, sorbitol, mannitol, methylglucoside, sucrose,hydroxy propylsucrose (hyprose) and mixtures thereof; their partialesters with'a carboxylic acid; polyhydroxy substituted acids such asgluconic, arabonic and glucoheptoic acids; their lactones; salts, e.g.,sodium, potassium and ammonium, and esters, e.g., CrC alkyl esters.

Exemplary of suitable hydrocarbon radicals for use in thedithiophosphinates include the alkyl radicals ethyl, npropyl, i-propyl,n-butyl, i-butyl, amyl, hexyl, octyl, nonyl, lauryl, stearyl, etc.; thearyl radicals phenyl, substituted phenyl, etc.; the aralkyl radicalsbenzyl, w-phenyl propyl, etc.; the alkaryl radicals tolyl, ethyl phenyl,Xylyl, etc.; the alkenyl radicals allyl, cinnamyl, butenyl, oleyl, etc.;the cycoalkyl radicals cyclohexyl, etc.; and the cycloalkenyl radicalscyclohexenyl, etc. If a substituted hydrocarbon radical is to beemployed the substituent group should be inert to the stabilizing effectof the stabilizer system. The hydrocarbon radical, R, may be the same ordifierent, An especially preferred dithiophosphinate compound is zincdicyclohexyl dithiophosphinate.

In addition to the homopolymers of vinyl fluoride, which are thepreferred vinyl fluoride polymers, there may be employed copolymers ofvinyl fluoride with other monoethylenically unsaturated monomers,copolymerizable therewith, wherein the vinyl fluoride is present insubstantial or in major amounts, i.e., at least 75% to 80% of the totalby weight. Examples are monoethylenichydrocarbons, e.g., ethylene,propylene, isobutylene and styrene; halogen-substituted monoethylenichydrocarbons, e.g., vinyl chloride, vinyl bromide, 1,1-dichloroethylene,1,1-difluoroethylene, difluorochloroethylene, trifluorochloroethylene,tetrachloroethylene, trifluoropropylene, difluoroisobutylene; vinylesters, e.g., vinyl formate, vinyl acetate, vinyl propionate, vinylbutyrate, vinyl benzoate, vinyl pivalate, vinyl stearate, vinylsalicylate and vinyl esters of inorganic acids; vinyl ethers, e.g.,vinyl ethyl ether, tetrafluoroethyl allyl ether and vinyl dioxolane;vinyl ketones, e.g., methyl vinyl ketone; N-vinyl imides, e.g., N-vinylsuccinimide and N-vinyl phthalimide; acrylic and methacrylic acids andtheir derivatives, e.g., esters, nitriles, amides, anhydrides and acidhalides, including methyl methacrylate, beta hydroxyethyl metacrylate,allyl methacrylate, acrylonitrile, N-butyl methacrylamide, etc.;derivatives of maleic and fumaric acids, e.g., diethylemaleate anddimethylfumarate; propenyl esters, e.g., allyl acetate, isopropenylacetate, etc. The presence of these copolymers or even a smallpercentage of a comonomer which, as a homopolymer, is normally moresoluble in the selected latent solvent than is the homopolymer of vinylfluoride, may render said copolymer sufliciently more soluble inaforementioned latent solvent as to permit its application on asubstrate containing considerably less solvent than is needed in theapplication of homopolymers of vinyl fluoride.

Suitable vinyl fluoride polymers have an intrinsic viscosity of at leastabout 0.35 and preferably at least about 0.75. The polymer particle mayrange in size up to about 30 microns in diameter, preferably thediameter of the polymer particles is below about 20 microns. The size ofthe polymer particle may be reduced by a variety of means known in theart, such as ball milling or grinding. Although particle sizes as low as0.005 microns may be employed, it is preferable that the size of theparticle be within the range of 0.05 to 5 microns. The particles in agiven dispersion need not be uniform in size.

The latent solvents which may be used in the dispersion system of thepresent invention generally have boiling points of at least about 100C., preferably boiling points above about 120 C., but below the point atwhich the vinyl fluoride polymer begins to deteriorate or degrade. Thelatent solvent employed need not necessarily be liquid at roomtemperature provided its melting point is not so high that thetemperature necessary for liquid blending of the latent solvent does notsubject the polymer to thermal degradation.

Following are examples of specific compounds representative of the classof latent solvents useful in the process of the present invention: gammabutyrolactone, butadiene cyclic sulfone, tetramethylenesulfone,dimethylsulfolane, hexamethylenesulfone, diallylsulfoxide,dimethylsulfoxide, dicayngbutene, adiponitrile, ethylene carbonate,propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate,isobutylene carbonate, trimethylene carbonate, N,N-diethylformamide,N,N-dimethylacetamide, N,N dimethylformamide, N,N dimethylgammahydroxyacetamide, N,N dimethyl-gamma-hydroxybutyramide,N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, N-methylacetamide,N-methylformamide, N,N-dimethylaniline, N,N-dimethylethanolamine, 2Fpiperidone, N-methyl-Z-piperidone, N-methyl-Z-pyrrolidone,N-ethyl-Z-pyrrolidone, N-isopropyl-Z-pyrrolidone,5-methyl-2-pyrrolidone, beta-propiolactone, delta-valerolactone, gammavalerolactone, alpha angelicalactone, beta-angelica-lactone,epsilon-carpolactone, and alpha, beta and gamma-substituted alkylderivations of gammabutyrolactone, gamma-valerolactone and deltavalerolactone, as well as delta-substituted alkyl derivatives ofdeltavalerolactone, tetramethyl urea, l-nitropropane, 2-nitropropane,acetonyl acetone, acetophenone, acetyl acetone, cyclohexanone, diacetonealcohol, dibutyl ketone, isophorone, mesityl oxide, methylamyl ketone,S-methylcyclohexanone, bis(methoxymethyl)uron, methylacetylsalicylate,diethyl phosphate, dimethyl phthalate, ethyl ace'toacetate, methylbenzoate, methylene diacetate, methyl salicylate, phenyl acetate,triethyl phosphate, tris- (morpholino)phosphine oxide,N-acetylmorpholine, isoquinoline, quinoline, pyridine andtris-(dimethylamido)- phosphate.

Of 'the many pigments employed white pigments have been the mostsuccessfully used in coating exterior surfaces. Titanium dioxide hasbeen the most widely employed white inorganic pigmentary substanceprobably because of a combination of innate properties it possesses,i.e., high refractive index, lack of color (whiteness), physical andchemical stability and relatively low specific gravity. Titanium dioxidepigments are classlfied as e1the r chalking or non-chalking.chalking-type pigment is characterized by a gradual film deteriorationto a powdery chalk which is removed by the eroding action of wind andrain to expose the underlying section to further attack a resulting in aprogressive wearing away of the coating system. Anatase crystalmodification of titanium dioxide exhibits this chalking characteristic.For most commercial coating applications, however, chalking-typepigments are not employed for the above reason.

.The rutile crystal modification of titanium dioxide, especially rutilecrystals treated with silicon, aluminum or zinc, exhibits non-chalkingcharacteristics. Like the chalking, crystal-type modification, anatase,color development also occurs with rutile during the baking operation.Unlike dispersion coating systems containing the chalking type pigment,dispersion coating systems containing the non-chalking type pigment aredifiicult to stabilize and are not necessarily stabilized with compoundsfound suitable to stabilize a system containing the chalking-typepigment. However, using the stabilization system of the presentinvention whatever form of crystal modification of titanium dioxide isemployed the resultant pigmented vinyl fluoride polymer coating isresistant to discoloration on baking and subsequent aging.

Inaddition to the reactive pigment the dispersion system may containother highly divided solid pigments, pigment extenders, fillers or thelike and other conventionally used compounding pigmented systems such aslithopone, zinc sulfide, iron oxide, mica china clay, mineral silicateand coloriferous agents. Also, protective colloids and pigmentdispersing or deflocculating agents, such as tetrasodium pyrophosphateor potassium tripolyphosphate may be employed.

The proportions of vinyl fluoride polymer, latent solvent, pigment andstabilizer may vary depending on the type of application and the methodof application desired. The amount of latent solvent is adjusted to givea fluid or sometimes viscous composition that is of suitable consistencyfor application to the particular substrate wh c s o be a ed Th s, ofcour will va y grea y according to the manner of application; forinstance, whether it is desired to spraythe dispersion on the substrate,to dip the substrate into the dispersion or to apply the dispersion onthe substrate with some sort of roller system as well as other factorssuch as temperature, type of liquid dispersants employed and the like.

Generally, however, from about 25 to 400 parts, preferably about 50 to200 parts, by weight, of latent solvent per 100 parts of vinyl fluoridepolymer have been found suitable. The stabilizer system may beincorporated into the resin system in stabilizing concentrations fromabout 0.05 to 7.5 parts, preferably about 0.1 to about 5 parts, byweight, based on 100 parts, by weight, of vinyl fluoride polymer. Theratio of the dithiophosphinate compound to polyol is within the range ofabout 0.25 to 4:1, preferably 0.5 to 1.5 :1, with an especiallypreferred ratio being 1:1. The pigment is present in the dispersionsystem within the range from about 5 to 75 parts, by weight, preferablyto 60 parts, by weight, per 100 parts, by weight, of vinyl fluoridepolymer.

In addition to the combination of the dithiophosphinate compound andpolyol in the stabilizing system a diester of a thiodialkanoic acidhaving the general formula S(CnH COOR) may also be employed, wherein nis an integer from about 1 to 8 and R is a hydrocarbon radical(aliphatic, straight or branched, cyclic or aromatic, saturated orunsaturated, substituted or unsubstituted) from about 6 to 20 carbonatoms, wherein R may be the same or different radicals.

Exemplary of suitable diesters of thiodialkanoic acid include dilaurylthiodipropionate, dimyristyl thiodipropionate, dicetyl thiodipropionate,distearyl thiodipropionate, dicinnamyl thiodipropionate,dibenzylthiodipropionate, dicyclohexylthiodipropionate, dilaurylthiodibutyrate, etc., and mixtures thereof, e.g., 70% dilaurylthiodipropionate, 20% dimyristyl thiodipropionate and 10% dicetylthiodipropionate. Preferably, the thiodialkanoic acid ester employed isdilauryl thiodipropionate. When the diester of a thiodialkanoic acid isalso employed the amount of each of the components of the stabilizersystem may be within the range from about 17% to 66%, by weight, of thetotal weight of the stabilizer system; preferably each of the componentsis present in the stabilizer system in equal proportions.

Other ingredients which generally are employed in dispersion coatingsystems may be added to the vinyl fluoride polymer dispersion system ofthe present invention. Exemplary of these additives are thickeningagents, i.e., polymethylmethacrylates, polymethylmethacrylate copolymersof acrylonitrile with methomethacrylate, vinyl resins, carboxy vinyls,cellulose acetate and the like; neutralizing agents, i.e., amines andthe like.

The vinyl fluoride polymer dispersion system may be prepared by blendingthe vinyl fluoride polymer, latent solvent therefor, pigment andstabilization system in a wide variety of mixing equipment, includingHobart mixers, Waring Blendors, ball mills, colloid mills, sand grindingequipment and the like. Advantageously, a pigment slurry containing thepigment, stabilization system and part of the latent solvent first isprepared in order to grind and disperse thoroughly the pigment beforeintroducing the vinyl fluoride polymer. Also, in order to facilitatefurther dispersing the vinyl fluoride polymer, a solvent solutioncontaining the remaining portion of latent solvent to be employed andother additives such as thickening agents and like ingredients may beprepared beforehand to ensure solution. Once the pigment slurry andlatent solvent solution have been prepared, the vinyl fluoride polymerthen may be incrementally added to the pigment slurry-latent solventsolution mixture in a high speed agitator followed by a ball milling ofthe resultant dispersion, if desired.

A great variety of substrates may be coated in accordance with thisinvention. For example, leather, cloth, resins, wood, stones, concrete,cement and of special interest coatings for metals including steel,aluminum, iron, magnesium and nickel andany alloy thereof. 7

After the vinyl fluoride polymer dispersion system of the presentinvention has been applied as a coating to the substrate, adhesion isachieved by employing heat to cure the dispersion system withoutdiscoloration or decomposition of the coating during baking. The heatcuring of the pigmented vinyl fluoride polymer dispersion system mayproceed by the method disclosed in Ser. No. 273,550, filed Apr. 17,1963. The method disclosed therein comprises heat curing the appliedvinyl fluoride polymer under controlled conditions involving heating thecoating at a temperature suflicient to coalesce the pigmented vinylfluoride polymer on the substrate and then heating the coalesced vinylfluoride polymer at a temperature of at least about 50 F. above'theinitial heat curing treatment. Alternatively, the applied pigmentedvinyl fluoride polymer dispersion coating may be heat cured in a singleheat treating step comprising heating the applied pigmented polyvinylfluoride dispersion coating at an elevated temperature, generally inexcess of about 450 F., for a suflicient period of time to effectadhesion of the coating to a substrate. This method is disclosed in Ser.No. 370,118, filed May 25, 1964.

In order that those skilled in the art may more completely understandthe present invention and the preferred method by which the same may becarried into effect the following specific examples are offered.

EXAMPLE 1 A series of white pigmented polyvinyl fluoride dispersionsystems containing titanium dioxide (Titanox RA- NC-Titanium PigmentCorp.) and employing various stabilizers are prepared having thefollowing recipe:

The polyvinyl fluoride employed has an intrinsic viscosity of 0.9. Thepigmented polyvinyl fluoride dispersion is prepared by first making apigment slurry and solvent solution and then incrementally mixing intothis mixture the polyvinyl fluoride. The ingredients are ground in aball mill for 24 hours after which the pigmented dispersion is deaeratedto remove all contained air.

The prepared pigmented polyvinyl fluoride dispersions are applied toalodized aluminum panels (6 x 12" chromate-treated aluminum panelssuppliedby Q-Panel Company, Cleveland, Ohio) by means of a Baker FilmApplicatorto give a dry film thickness of about 1 mil. The wet films areheated in a hot air circulating oven at 500 F. for various time periods.Observations are then made concerning color retention and adhesion ofthe finished pigmented coating. The particular stabilizers employed anddata obtained from the color retention test and adhesion test for eachcoating are reported in Table I, below.

The adhesion test comprises cross-scoring a one-inch square portion ofthe coated surface with score marks ,4 apart. The scored surface is thensubjected to a reverse impact of 70 inch-pounds on a Gardner ReverseImpact Instrument. Scotch tape #600 is pressed over the impacted, scoredcoated area and then quickly removed. Adhesion failure is indicated byremoval of any portion of the coating by the tape. If no portion of thecoating is removed the adhesion is considered adequate.

For convenience, the stabilizers tested are coded as follows:

TABLE I Time (Minutes) Concentration 2 3 4 5 6 7 Stabi- (parts per RunNo. lizer hundred) Color AD Color AD Color AD Color AD Color AD Color AD1.0 W P OW 1.5 W P OW 2.0 W P OW 1.0 W F OW 1.5 W F W 2.0 W F W 1.0 W PW 1.5 W P W 2.0 W P W 1.5 W F OW 3.0 W F W 1.5 W F OW 3.0 W F OWConcentration 8 9 10 ll 12 Stabi- (parts per Run N0. lizer hundred)Color AD Color AD Color AD Color AD Color AD 2 A 1.5. 3 A 2.0. 4 B 1.0.B 1.5. 6 B 2.0. 7 C 1.0. 8 0 L5 9 C 2l0 D 1.5 11 D 3.0. 1- E 1.5. 13 E3.0

Code.-Color: W=wlIite, OW=color change, SS=slightly spotted, S=spotted.Adhesion: F=failed, P=passed.

EXAMPLE 2 Stabilizer system: Code Example 1 is a repeated except thatstabilizer systems Zmc g q dlthlophosphmate'Hrlpenta' are employedcomprising a combination of ingredients. i r- Each of the compounds inthe stabilizer system is present me F O exyl dlt 10p osphmatei'dlpenta'in equal amounts. For convenience the stabilizer systems "T"? "i Itested are identified and coded as follows: Zmc dlqyclohewldlthlophosphmi'ite+lEnpenta' erythr1tol+d1lauryl 3,3 th1od1pr0p1onate JStabilizer system: Code Dilauryl 3,3 thiodipropionate+tripentae- Thedata obtained from the color retention test and rythritol G adhesiontest for each of the stabilizer systems are re- Dilauryl 3,3thiodipropionate+tripentaeryported in Table II, below.

thritol G TABLE II Time (Minutes) Concentration 2 3 4 5 6 (parts perhundred) Color AD Color AD Color AD Color AD Color AD 1.5 W F OW F 3.0 WF OW F 1.0 W P W P 0W P 2.0 w F W P W P 0.5 W P W P W P 1.0 W F W F W P2.0 W F W F W F 0.5 W F W P W P 1.0 W F W F W P 2.0 W F W F W F 0.9 w FW P W P 1.5 W F W P W P 2.0 W F W F W F Time (Minutes) Concentration 7 89 10 11 Stabi- (parts per Run No. lizer hundred) Color AD Color A-DColor AD Color AD Color AD 1 F 2 F 3 r G 4 G 5 H (I H 7 H s I 9 I 10 I11 J 12 .T 13 J 1 Coating color remains white to 14 minutes at 500 F.

2 Coating color remains White to 13 minutes at 500 F.

3 Coating color remains white to 12 minutes at 500 F.

Code.-C0lor: W=white, OW=oolor change, SS=sl1ghtly spotted, S=sp0tted.Adheslon: F=fa1led, P=passed.

It can be seen from the data in Table II employing the stabilizationsystem of the present invention, i.e., runs to 13, excellent colorstability and adhesion is attained. Further, employing dilaurylthiodipropionate (Run 13) in combination with equal parts of zincdicyclohexyl dithiophosphinate and polyol also permits the coating .toattain excellent color stability while achieving adhesion.

It is to be understood that although the invention has been describedwith specific reference to particular embodiments thereof, it is not tobe so limited since changes and alterations therein may vbe made whichare within'the full intended scope of this invention as defined in theappended claims.

It is claimed:

1. A composition of matter consisting essentially of a vinyl fluoridepolymer containing at least 75% by weight of the total weight of apolymer of vinyl fluoride and 0.05 to 7.5 parts, by weight, per 100parts, by weight, of said polymer of a stabilizer of a mixture of analiphatic polyol selected from the group consisting ofdipentaerythritol, tripentaerythritol and mixtures thereof and zincdicyclohexyl dithiophosphinate wherein the ratio of the zincdicyclohexyl dithiophosphinate to the aliphatic polyol is within therange of about 0.25 to 4:1, said composition having heat stability andadhesion characteristics at elevated temperatures.

2. The composition of claim 1 wherein the stabilizer is present inamounts from 0.1 to 5 parts, by weight, per 100 parts, by weight, ofvinyl fluoride polymer.

3. A composition of claim 1 which additionally contains a latent solventfor the vinyl fluoride polymer and apigment.

4. The composition of claim 3 wherein the pigment is titanium dioxide.

5. The composition of claim 4 wherein the titanium dioxide pigment isnon-chalking.

6. The composition of claim 1 wherein the stabilizer additionallycontains a thiodialkanoic acid ester having the formula:

wherein n is an integer from about 1 to 8 and R is a hydrocarbon radicalfrom about 6 to 20 carbon atoms, and wherein each of the components ofthe stabilizer system is present in an amount of from about 17% to 66%by weight of the total weight of the stabilizer system.

7. The composition of claim 6 wherein the thiodialkanoic acid ester isdilauryl thiodiproprionate.

8. The composition of claim 1 wherein the polyol is tripentaerythritol.

9. The composition of claim 1 wherein the polyol is dipentaerythritol.

10. The composition of claim 3 which comprises 100 parts, by weight,vinyl fluoride polymer, 25 to 400 parts, by weight, latent solventtherefor, 5 to 75 parts titanium dioxide pigment based on the weight ofpolymer and 0.05 to 7.5 parts, by weight, of stabilizer, based on theweight of polymer.

11. The composition of claim 1 wherein the dithiophosphinate compoundand polyol are present in equal amounts.

12. The composition of claim 6 wherein each of the thiodialkanoic acidester, polyol and dithiophosphinate compound is present in thestabilizer in equal amounts by weight.

13. An anticle of manufacture which comprises a substrate coated with apigmented vinyl fluoride polymer, said coating being prepared from adispersion system consisting essentially of a vinyl fluoride polymercontaining at least by weight of the total weight of a polymer of vinylfluoride, a latent solvent therefor, a pigment and a stabilizer of amixture of an aliphatic polyol selected from the group consisting ofdipentaerythritol, tripentaerythritol and mixtures thereof and zincdicyclohexyl dithiophosphinate wherein the ratio of the zincdicyclohexyl dithiophosphinate to the aliphatic polyol is within therange of about 0.25 to 4:1, said coating having heat stability andadhesion characteristics at elevated temperatures.

14. The article of claim 13 wherein the stabilizer additionally containsan ester of a thiodialkanoic acid having the general formula:

S (CnH COOR) 2 wherein m is an integer from about 1 to 8 and R is ahydrocarbon radical from about 6 to 20 carbon atoms, and wherein each ofthe components of the stabilizer system is present in an amount of fromabout 17% to 66% by weight of the total weight of the stabilizer system.

15. The article of claim 13 wherein the substrate is metal.

References Cited UNITED STATES PATENTS 3,293,208 12/1966 Milion-is et al26045.75 2,479,957 8/1949 Newkirk 26045.75 2,797,238 6/ 1957 Miller etal 260500 2,861,052 11/1958 Elliott 26045 .75 2,935,491 5/1960 Mack26045.75 3,081,208 3/1963 Bottorf et al. 260 92.1 3,139,470 6/ 1964Prengle et al. 264-289 3,281,381 10/ 1966 Hechenbleikner et al.

260-45 .95 3,325,444 6/ 1967 Best et al 26045.75 3,320,206 5/1967 Neros2601-41 3,190,852 6/ 1965 Doyle 260-45.75 3,267,069 8/1966 Cummings260-45.75

FOREIGN PATENTS 1,391,270 1/1965 France.

ALLAN LIEBERMAN, Primary Examiner.

US. Cl. X.R.

